Unable to get tach sync - MS3 - Jimstim - Miata Turbo Forum - Boost cars, acquire cats.

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Old 10-27-2011, 10:36 PM   #1
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Default Unable to get tach sync - MS3 - Jimstim

I am waiting for my stuff to arrive to build my jumper harness to go parallel with my stock ECU on a 2001.

I configured the MS3 thus: (only listing ignition related stuff)
Tachselect to VRIN
TSEL to VROUT
VRIN to 1K ohm to 5v in prototype area

R52 full counter clockwise
R56 clockwise 6 turns from fully CCW.

When I meter from pin 3 of U7 to R54, I get .03v, but from R54 to pin 2 of U7 I can get to about 3v if I bring r56 back a turn or two. Something about this doesn't make sense. I should be reading 3v or so to pin 3 of U7 according to everything I have read. Is the Pullup my problem?

What I am trying to do is get some indicated RPM so I can start testing my spark and fuel (LEDs on MS3x card).

When I do the jumper test on the JIMSTIM itself I get a flashing LED that tracks with the RPM C potentiometer - so I believe the JimStim is working properly.

Can you all help troubleshoot me and get me straightened out?

Thanks!
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File Type: csv 2011-10-27_18.15.37.csv (68.0 KB, 54 views)
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Old 10-27-2011, 10:46 PM   #2
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You'll get no RPM indication until you have both the cam and crank sensor connected.

When taking voltage measurements, always measure between one point in the system and ground, not between two points in the system. IOW, measure between R54 and GND, adjusting R56 to achieve ~ 2.5v.

Since you are running parallel, you probably don't need the pullup resistors on the inputs. The stock ECU is providing a pullup.

edit: You'll still need a pullup so long as you're on the stim, but you can set a pullup jumper on that.

Also, moving this to the MS forum.

Last edited by Joe Perez; 10-27-2011 at 10:58 PM.
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Old 10-27-2011, 11:11 PM   #3
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Thank you sir, I meant to post it on the MS forum I just got sidetracked.

I set R56 (at R54 to ground) to 2.6V.

I re-installed the MS3x expansion board.

Set R11 on the expansion board (R17 to ground) to 2.3v where it topped out. Is this a problem? (I am so used to problems...)
Going off of some stuff on http://westfieldmx5.devocht.com/?page_id=995

Thanks again Joe.

What next?
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Old 10-27-2011, 11:24 PM   #4
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Quote:
Originally Posted by Chiburbian View Post
Set R11 on the expansion board (R17 to ground) to 2.3v where it topped out. Is this a problem? (I am so used to problems...)
2.3v is fine, this isn't a highly precise setting. The absolute minimum for capture is somewhere around 0.7 - 1v, to compensate for the forward drop across the output of the sensor. I like to set it in the midrange of the actual signal sweep (which is appx 1 - 5v) just to give it some headroom and noise immunity.



Quote:
What next?
With both the crank and cam signals connected, the pots set, and the software configured for '99 Miata inputs and MS3X, you should be able to see an RPM indication.
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Old 10-27-2011, 11:37 PM   #5
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Ok... we are getting somewhere.

JimstimX connected.
Jumper to 5V on Jimstimx.
Jumper from Secondary trigger to cam header on StimX.


I am getting some tach signal now, but its jumping from zero to whatever I set my pot at.

Very unstable. Its cool that my "spark" LEDs on the JimstimX are finally lighting though. That is a first for me.

Tooth Logger still doesn't seem to give me any useful data. What can I log that can help you guys in troubleshooting me?
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Old 10-28-2011, 07:16 AM   #6
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Try a different mode on the Jimstim and in Tunerstudio.
I have a plain Jimstim, but I have never been able to get a tach signal on in 99-00 mode. Like you, I only get the flashing signal. When I set the Jimstim to CAS4/1 (and Tunerstudio as well), I do get an rpm reading.
When installing in the car, obviously I set it back to 99-00.
FWIW, $0.02, YMMV etc .
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Old 10-28-2011, 10:49 AM   #7
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with frank's circuit, I get perfect sync with the jimstim in 99-00 and on the car.

Chiburbian, make use of the diagnostics tab and take some composite logs.
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Old 10-28-2011, 11:21 AM   #8
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Quote:
Originally Posted by f_devocht View Post
Try a different mode on the Jimstim and in Tunerstudio.
I have a plain Jimstim, but I have never been able to get a tach signal on in 99-00 mode. Like you, I only get the flashing signal. When I set the Jimstim to CAS4/1 (and Tunerstudio as well), I do get an rpm reading.
When installing in the car, obviously I set it back to 99-00.
FWIW, $0.02, YMMV etc .

that's odd, ive never had the issue.
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Old 10-28-2011, 12:04 PM   #9
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Input edge capture could be set backwards.
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Old 10-28-2011, 02:50 PM   #10
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When I get home from work I will do a composite log and post. Thx all.
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Old 10-28-2011, 08:24 PM   #11
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Here is a composite log at an unstable 2800rpm.

(this is with Miata 99-00 settings on ecu and jimstim)

Switched to CAS 4/1 for testing purposes on stim and ECU. Got stable RPM.

Do I just test everything with 4/1 then switch back to 99-00 when I plug it into my car?
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